Freelance Senior OR Junior Full Stack Developer – React / Next.Js / Node.Js – BarcelonaYou will collaborate closely with the Tech Lead, Product Owner, UX Designer, and Data team to design, develop, and deliver high-quality features within an agile environment.ResponsibilitiesDevelop and maintain complex, data-heavy user interfaces using React and Next.JsBuild and optimise reusable components and contribute to the internal UI libraryDesign and integrate REST APIs and WebSocket endpointsEnsure code quality through clean architecture and best practicesWrite unit and integration tests (Jest / Testing Library)Collaborate with Product, UX, and Data to deliver features end-to-endParticipate in architecture discussions and decision-makingTroubleshoot and resolve issues across the stackContribute to CI/CD processes and development workflow improvementsMaintain documentation on ConfluenceRequired Qualifications3-5+ years of experience as a Full Stack or Front-End EngineerStrong hands-on experience with React.Js and Next.JsExperience building and consuming REST APIsGood understanding of backend technologies (Node.Js required; Python/FastAPI is a plus)Experience with component libraries, design systems, or shared UI componentsFamiliarity with modern testing frameworks (Jest, Testing Library)Good understanding of performance, security, and scalability principlesComfortable working in cross-functional agile teamsStrong communication skills in EnglishNice to HaveExperience with container technologies (Docker, AWS ECR/EKS, OpenShift)Experience with CI/CD pipelinesKnowledge of SonarQube, Checkmarx, or similar code quality toolsExperience in healthcare, pharma, or other regulated environmentsWhat We OfferFull-time freelance mission3-month contract, renewable depending on performance and roadmapHybrid environment from BarcelonaSeniority levelMid-Senior levelEmployment typeFull-timeJob functionInformation TechnologyIndustriesPharmaceutical ManufacturingBarcelona, Catalonia, Spain#J-18808-Ljbffr

📌 Freelance Senior Or Junior Full Stack Developer – React / Next.Js / Node.Js – Barcelona (Madrid)
🏢 Blu Selection Recruitment Agency
📍 Madrid